WhatsApp isn't the only messaging game in town

Facebook sure made headlines last week when it agreed to purchase WhatsApp for $19 billion (in cash and stock). An extremely popular cross-platform messaging app, WhatsApp is available for iOS, Android, BlackBerry, and even Windows Phone. Basically, equipped with WhatsApp, you can potentially reach anyone who owns a mobile device.

Why is WhatsApp so special (and why would Facebook be willing to fork over so much for it)? Well, it supports full multimedia texting, so you can send video, photos and voice notes in addition to text. Perhaps most critically, WhatsApp makes it easy to send bulk messages and carry on group texts. You can build multiple groups of contacts and start a chat with them with just a few taps. Groups can contain up to 10 members.

And getting set up with WhatsApp is a snap. There's no username and login process. The app simply uses your phone number, making it easy to install and easy to migrate from one phone to another.

Might some of that change with Facebook as WhatsApp's new owner? Many existing users have expressed concern about the purchase, worrying that Facebook would eliminate the app as a stand-alone product and incorporate it into the larger social network, or at the very least change its attractive pricing model (first year is free, then $1 a year thereafter).

If you're among that group, don't worry -- there's little to be concerned about. Plus, earlier this week WhatsApp announced it would introduce free voice-calling service. But if you want to hedge your bets, many other messaging apps are out there, though admittedly, finding one as good as WhatsApp is likely to be a problem, which is one reason Facebook targeted it as an acquisition. Here's a quick rundown of WhatsApp rivals:

Kik. Kik is popular and free, and is one of the few apps with platform support as wide as WhatsApp's. You can get it for iOS, Android, Windows Phone and BlackBerry. It's a solid one-to-one texting app, and it even has its own integrated browser, so tapping links keeps you inside the app rather than ejecting you to an external browser.

Line. This app looks a little childish. Line features virtual stickers, and the webpage looks optimized for grade-schoolers. But while WhatsApp just announced that it would soon support voice calls, Line distinguishes itself by doing that (and free video calls) right now.

GroupMe. Despite an abundance of texting apps, few do group texting nearly as well (or at all) as WhatsApp. That's where GroupMe comes in. This app offers free group messaging on almost all the mobile operating systems that WhatsApp supports -- iOS, Android and Windows Phone.

Wickr. If privacy is a high priority for you, then check out Wickr. Available for free for both iOS and Android, this app's primary claim to fame is that it creates self-destructing text messages. Before you send a message, you can choose how long the message persists (anywhere from mere moments to several days). When the timer expires, the text message does, too, so the recipient no longer retains a copy.

Photo courtesy WhatsApp